In this study, a two-bed electrically-heated regenerative catalytic oxidizer (RCO) was used to test the destruction characteristics in burning toluene-borne air streams. The RCO contained two 0.152 m¡Ñ0.14 m¡Ñ1.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0111 m and a height of up to 0.875 m with a void fraction of 0.42 in the packed section. In addition, in each column catalytic particles with an average diameter of around 0.008 m were packed over the gravel particles to a height of 0.125 m. Gas temperature rise and the gas pressure drop over the beds were also studied. Experimental results reveal that, with a valve shifting time (ts) of 1.5 min, superficial gas velocities (Ug) of 0.39 and 0.86 m/s (evaluated at an influent air temperature of around 30 oC) and preset maximum destruction temperatures (TS) of 300-400 oC, only around 25% of the influent toluene (Co = 200-400 ppm) was thermally destructed with no catalyst in both beds. With the cartalyst packings and operation conditions of Ug = 0.39 m/s and Co = 200-800 ppm, destruction efficacies of around 80.9¡Ó0.8, 94.6¡Ó1.8, and 98.1¡Ó0.2 % were observed, respectively, at TS of 250, 300, and 400 oC. At Ug = 0.86 m/s and Co = 200-800 ppm, destruction efficacies of around 69.7¡Ó3.1, 93.9¡Ó1.7, and 97.8¡Ó0.4 % were observed, respectively, at TS of 250, 300, and 400 oC. It is suggested that operation conditions with Ug = 0.39-0.86 m/s (equivalent to empty-bed-residence times of 0.29-0.64 s for the gas at 30oC through the catalyst beds) and TS = 300 oC are suitable for the destruction of around 98% of the influent air with 200-800 ppm toluene. Gas temperature rises of 21 and 26 oC, respectively, were found for Ug = 0.39 and 0.86 m/s with TS = 300 oC. The Ergun equation was found to suffice in the estimation of the pressure drop when the gas flowed over the packing beds.

Nitrogen is an essential constituent and building unit of all living organisms, and the primary limiting nutrient on our planet such that its cycle widely depends on the diverse nitrogen-transforming microorganisms, such as denitrifiers. Oxygen minimum zones or hypoxic aquatic ecosystems account for 30-50% of all nitrogen denitrification and under dynamic transformation imbalance, of measure dependent variable modularity, little is known about discrete shifts in denitrification competition by various microorganisms of divergent metabolism; or the Fe (II) – Fe (III) redox linking process. Novel nitrate dependent Fe (II) oxidizing bacteria as rapid denitrifier and iron oxidizer can significantly oxidize various iron minerals (magnetite and ferrous mono sulfide). Evidence of nitrate dependent Fe (II) oxidation by the bacterium P. ferrooxidans sp. MAI-1 could shed light as a novel competitor at microaerophilic (<2.0mg/L DO, -100 – +100 mV) interfacial competition with cyanobacteria Microcystis aeruginosa corollary to ecosystem eutrophication and concomitant microcystin production, with the goal of abating a toxic cyanobacterial bloom. Nitrate Dependent Iron Oxidizing Bacteria (NDFe(II)OB) showed rapid nitrate reduction (>25 mg/L NO2, day 7) and consequent bright-orange iron oxides. Saturation indices (day 1 and 8 SI = log (IAP/Ksp), showed non exclusive vivianite formation i.e., 3.80 and 0.44-0.55, respectively, with near complete oxidation by day 8, significantly abating logarithmic growth over a fourteen day period (p>0.01). N-N dichotomies are not purely exclusive, as terminal PO4 competition differed by ~0.1 mg/L after a 15 day period, with approximately one five hundred times more N-nitrogen loss compared to P-phosphorus loss difference. Early logarithmic cyanobacteria cell counts under the presence of the competitor decreased by >20% by day 18 of growth. This is consistent with the classical view that under primary metabolite exhaustion, interspecific competition should lead to competitive exclusion and not niche differentiation.

A hybrid rocket is a propulsion system that uses propellants in two different phases, typically a solid fuel inside the combustion chamber and a separate gaseous or liquid oxidizer stored in a tank. Hybrid rockets are an area of research interest because of their low explosive risk, inexpensive components, and high degree of reliability. In the Propulsion Research Laboratory at Utah State University, pure oxygen is among the top choice for hybrid rocket oxidizers due to its low cost and ease of storage. When paired with a solid fuel known as ABS (acrylonitrile butadiene styrene) plastic, specific impulse values exceed 200 seconds at one atmosphere. This metric outperforms hydrazine, which is a propellant standard for in-space propulsion that exhibits high vapor toxicity and explosive hazards. However, due to the low density of oxygen, propulsion applications require storage pressures up to 3000 psig. At this high pressure, the use of oxygen can present a fire hazard. As a result, this thesis investigates the feasibility of replacing oxygen with a moderately enriched compressed air containing oxygen levels up to 40%, while maintaining performance metrics equal to or above hydrazine. To demonstrate the performance of moderately enriched air as a hybrid rocket oxidizer, comparisons to tests using pure oxygen are presented.

Performance studies on the treatment of VOCs in air streams by a pilot-scale regenerative catalytic oxidizer (RCO) and a full-scale regenerative thermal oxidizer (RTO) were conducted. The pilot-scale RCO was constructed with two 20-cm x 200-cm (inside diameter x packing height) regenerative beds packed with gravel (average particle size = 1.25 cm) used as the thermal regenerative solid material. Experimental results indicate that destruction efficiencies of 97 and 90%, respectively, were obtained for methyl ethyl ketone and toluene at a superficial gas velocity of 0.372 m/s (evaluated at 25¢J) and a maximum bed temperature of 400¢J. It was estimated that an electrical thermal energy of approximately 84 kWh was required for treating 1,000 m3 of the waste air stream by the RCO. The full-scale RTO was constructed with two regenerative beds of 100-cm square x 200-cm height packed with the gravel used in the RCO. A paint solvent containing methyl ethyl ketone, ethyl benzene, xylenes, and ethyl acetate was used for the target VOCs. Experimental results indicate that, at a superficial gas velocity of 0.372 m/s (evaluated at 25¢J), VOC destruction efficiencies of 84, 92, 95 and 98% were obtained for the beds at temperature ranges of 200-300, 300-500, 400-700, and 500-700¢J. These conditions corresponded to empty gas retention times of 1.07, 0.85, 0.41, and 0.39s, respectively, for the cited temperature ranges. Finally, it was estimated that electrical watts of approximately 0.10, 0.45, 1.78, 2.43 kWh were required for treating 1,000 m3 of the waste air stream, respectively, at bed temperature ranges of 200-300, 300-500, 400-700, and 500-700¢J.

Unbroken gel and residue from guar-based fracturing gels can be a cause for formation damage. The effectiveness of a fracturing treatment depends on better achieveing desired fracture geometry, proper proppant placement and after that, a good clean-up. The clean-up is achieved by reducing the fluid viscosity using chemical additives called "Breakers". There are many different types of breakers used in the industry, but they can be broadly divided into two categories: oxidizers and enzymes. Breaker perfromance depends on bottomhole temperature, breaker concentration and polymer loading. Different kind of breakers, used at different concentrations and temperatures, give different kind of "break" results. Therefore, the amount of unbroken gel and residue generated is also different. This project was aimed at studying basic guar-breaker interactions using some of the most common breakers used in the industry. The breakers studied cover a working temperature range of 75 degrees F to 300 degrees F. The effectiveness of each breaker was studied and also the amount of damage that it causes. Viscosity profiles were developed for various field concentrations of breakers. The concentrations were tested over temperature ranges corresponding to the temperatures at which each breaker is used in the field. The majority of these viscosity tests were 6 hours long, with a few exceptions. Early time viscosity data, for the intial 10 minutes of the test, was also plotted from these tests for fracturing applications where the breaker is required to degrade the fluid by the time it reached downhole. This was needed to prevent the damage to the pumping equipment at the surface yet still have almost water-like fluid entering into the formation. The study provides a better understanding of different breaker systems, which can be used in the industry, while designing fracturing fluid systems in order to optimize the breaker performance and achieve a better, cleaner break to minimize the formation damage caused by polymer degradation.

In this study, a pilot-scale Regenerative Thermal Oxidizer (RTO) was used to test its performance for volatile organic compound (VOC) destruction and degree of thermal energy conservation. The RTO is electrically heated and contains two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) columns both packed with gravel particles of 1.0 cm in diameter to a height of 1.4 m. The bed has a void fraction of 0.415. The purpose of this study is to establish the influencing operating conditions and to improve the technique for further applications. Experiments include two phases: (1) energy conservation test with no VOC in the influent air stream , and (2) VOC destruction test with influent air streams containing one of the three VOCs: isopropyl alcohol, acetone, and xylene. Phase 1 experiments were conducted in the maximum gravel temperatures (Tmax) of 402-704 oC, superficial gas velocities (Ug, evaluated at ambient temperatures of 25-30 oC) of 0.15-0.50 m/s, and bed shift times (ts) of 0.5-2.0 min. Results indicate that the temperature raise (

No description available.

This thesis set out to find a blend of thermoplastics that had better combustion properties than the current ABS (acrylonitrile butadiene styrene) plastic or “Lego TM plastic” used by Utah State University. The current work is in an effort to eliminate toxic propellants from small space applications. High and low density polyethylene plastics were used because they are common plastic waste items. In this way rocket fuel can be made from these items to reduce the waste found in landfills. Three plastics were considered for replacement and as mixture components with the ABS plastic, namely low and high density polyethylene, and high impact polystyrene. These plastics failed to have superior combustion properties when used in rockets designed to achieve 12 pounds or less of thrust compared to the current ABS plastic.

In this study, two regenerative thermal oxidizers (RTO) were used to test the thermal destruction, thermal recovery efficiency and the gas pressure drop over the beds characteristics when burning, respectively, airborne chlorine- and nitrogen-containing volatile organic compounds (VOCs). First, an electrically-heated RTO containing two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0116 m and a height of up to 1.48 m with a void fraction of 0.41 in the packed section was used to study the destruction characteristics of chlorine-containing VOCs (trichloroethane, TCE and dichloromethane, DCM). With a valve switch time (ts) of 1.5 min, preset maximum destruction temperatures (TS) of 500-800 oC and superficial gas velocity (Ug) of 0.17-0.33 m/s (evaluated at an influent air temperature of around 27 ¢J), tests on the thermal recovery efficiency (TRE) and the pressure drop for the air stream without VOC in the influent air stream have been performed. With a ts of 1.5 min, Ts of 500-800 oC and Ug of 0.17-0.24 m/s (evaluated at an influent air temperature of around 27 ¢J), tests on the degree thermal destruction of VOCs with influent air streams containing one of the two VOCs: trichloroethylene (TCE) and dichloromethane (DCM) have been done. Second, an electrically-heated RTO containing two 0.152 m ¡Ñ 0.14 m ¡Ñ 1.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0111 m and a height of up to 1.0 m with a void fraction of 0.42 in the packed section was used to study the destruction and NOx formation characteristics of DMF (N, N-dimethylformamide). With a ts of 1.5 min, Ts of 750-850 ¢Jand Ug of 0.39-0.78 m/s (evaluated at an influent air temperature of around 30 ¢J), TRE and the pressure drop for the air stream without VOC in the influent air stream have been tested. With a ts of 1.5 min, a Ug of 0.39 m/s (evaluated at an influent air temperature of around 30 ¢J), and Ts of 750-950 ¢J and, thermal destruction efficiencies and nitrogen oxides (NOx) formation characteristics in burning air streams containing either DMF or DMF mixed with methyl ethyl ketone (MEK) were performed. Results demonstrate that: (1) a RTO is suitable for destruction of low concentrations (<1,000 ppm as methane) of airborne highly chlorinated VOCs such as TCE and DCM and the destructed products contain no chlorine and only trace of COCl2 (< 1% of the influent VOC); (2) for TS = 800 oC and Ug = 0.17-0.24 m/s, complete oxidation products of TCE and DCM are HCl, CO2, and H2O, and the main intermediates are CO and COCl2; (3) with ts of 1.5 min, a Ug of 0.39 m/s (evaluated at an influent air temperature of around 30 oC) and TS of 750-950 ¢J, no NOx was present in the effluent gas from the RTO when it was loaded with DMF-free air; (4) when only DMF was present in the influent air, the average destruction efficiencies exceeded 96%, and increased with the influent DMF concentration from 300 to 750 mg/Nm3. The ¡§NOx-N formation/DMF-N destruction¡¨ mass ratios were in the range 0.76-1.05, and decreased as the influent DMF concentration increased within the experimental range; (5) when both DMF and MEK were present in the influent gas, the NOx formation ratio was almost the same and the DMF destruction efficiency increased with the influent MEK/DMF ratio from 150/300 to 4500/300 (mg/mg) and in the preset temperature range. The NOx formation ratios were in the range 0.75-0.96; (6) the TRE decreased as Ug increased but was invariant with Ts; and (7) the Ergun equation was found to suffice in the estimation of the pressure drop when the gas flowed over the packing beds.

Volatile organic compounds (VOCs) can detrimentally affect human health directly and indirectly. However, the main environmental concern of VOCs involves the formation of smog. In the presence of nitrogen oxides, VOCs are the precursors to the formation of ground level ozone. Isopropyl alcohol (IPA) and toluene are extensively used in industry as solvents. They are all highly toxic to animals and humans. Accordingly, IPA and toluene are strongly associated with problems of VOCs. Catalytic incinerations and a regenerative catalytic oxidizer (RCO) were adopted to decompose VOCs herein. Various catalysts were prepared and developed in this study. The screening test of catalytic activity and the influences of the operational parameters on VOCs removal efficiencies were widely discussed through catalytic incinerations of VOCs. The more effective and cheaper catalysts through above discussions of catalytic incineration were selected. And they were utilized in an RCO to investigate their performance in VOCs oxidation and RCO operations. Experimental results demonstrate that 10 wt%CuCo/(G) catalyst performed well in an RCO because it has the excellent performance in incineration efficiency and economic efficiency. The achievements of this study are summarized as follows: (1) Treatment of isopropyl alcohol (IPA) using ceramic honeycomb(CH) catalyst The eighteen ceramic honeycomb catalysts we prepared by various methods (co-precipitation, wet impregnation and incipient impregnation), various metal weight loadings (5 ~ 20 wt %), and various metals (Cu and CuCe) were used in the experiment. The results indicate that 20 wt%CuCe/(CH) catalyst prepared by wet impregnation had the best performance in CO2 yield because TC50 and TC95 were 245¢J and 370¢J, respectively, under the following operating conditions; a space velocity of 12000 hr-1, an inlet IPA concentration of 1600 ppm, an oxygen concentration of 21%, and a relative humidity of 25%. Given the operational parameters of IPA oxidation experiments, the CO2 yields increased with higher temperature and oxygen concentration, but decreased with inlet IPA concentration, space velocity and the relative humidity increased. Moreover, the stability test results show that the 20 wt%CuCe/(CH) catalyst had excellent stability. (2) Treatment of toluene using molecular sieve(MS) catalyst Molecular sieve catalysts with various metals (Cu, Co, Mn, CuMn, CuCo, MnCo) and various loadings (5~10 wt %) were produced by wet impregnation to treat toluene. The results indicate that 10 wt%CuCo/(MS) had the best performance in toluene conversion because T50 and T95 were 295¢J and 425¢J, respectively, at an influent concentration of toluene of 900 ppm, an oxygen concentration of 21%, a space velocity of 12000 hr-1, and a relative humidity of 26%. The conversions of toluene increased with the reaction temperature and the influent concentration of oxygen, but decreased as the initial concentration of toluene and the space velocity increased. Moreover, we did not find any decay between the fresh and used catalysts using SEM and EDS. (3) Treatment of isopropyl alcohol (IPA) using Cu/(CH) and CuCo/(CH) catalysts We used the 20 wt% CuCo/(CH) and 20 wt% Cu/(CH) catalysts in a pilot RCO to test IPA oxidation performance under various conditions. The best catalyst was selected, and the economic efficiency of RCO and the phenomenon of RCO operations were more widely discussed. The results demonstrate that 20 wt% CuCo/(CH) catalyst performed well in an RCO because it was effective in treating IPA, with a CO2 yield of up to 95%. It also had the largest tolerance of variations in inlet IPA concentration and gas velocity. The 20 wt% CuCo/(CH) catalyst in an RCO also performed well in terms of TRE, pressure drop and selectivity to CO2. The thermal recovery efficiency (TRE) decreased as gas velocity increased. The temperature difference (Td) and pressure drop increased with gas velocity and heating zone temperature. The TRE range was from 87.8 to 91.2 % and the Td ranged from 22.1~35.1¢Junder various conditions. Finally, the stability test results indicate that the 20 wt% CuCo/(CH) catalyst was very stable at various CO2 yields and temperatures. (4) Treatment of toluene using CuCo/(CH) catalysts with various carriers In this work, three catalysts (10 wt%CuCo/(G)¡B10 wt%CuCo/(MS) and 20 wt% Cu/(CH)) were prepared by wet impregnation, and used in an RCO to test their performance in incineration efficiency and economic efficiency under various operational conditions. Then the best catalyst was selected and the phenomenons of RCO operations were further investigated. Experimental results demonstrate that 10 wt%CuCo/(G) catalyst performed well in an RCO because it is effective in treating toluene with a toluene conversion of up to 95% at the heating zone temperature (Tset) = 400¢J under various conditions. The 10 wt% CuCo/(G) catalyst had the greatest tolerance against the effects of inlet toluene concentration and gas velocity, and exhibited the best performance in terms of TRE , Td and pressure drop. The TRE range was from 90.2 to 92.9 % and Td ranged from 18.2 to 30.9¢J under various conditions at Tset = 300~400¢J. Moreover, when 10 wt% CuCo/(G) catalyst was used in an RCO, the results demonstrate that (1) high selectivity to CO2 ; (2) decrease in TRE and increase in Td as increasing the shifting time; (3) an insignificant effect of shifting time on pressure drop and (4) excellent stability of 10 wt% CuCo/(G) catalyst in a long period test.